* {
    margin: 0;
    padding: 0;
}

.input-box {
    margin-top: 20px;
    text-align: center;
}

#display {
    margin-top: 30px;
    width: 100%;
    text-align: center;
    font-weight: bolder;
    box-sizing: border-box;
}

#display::after {
    content: '';
    display: block;
    clear: both;
}

.node {
    height: 40px;
    line-height: 40px;
    float: left;
    box-sizing: border-box;
    border: 1px solid rgba(99, 99, 99, .7);
}

.level0 {
    width: 100%;
    background-color: green;
    font-size: 28px;
}

.level1 {
    width: 50%;
    background-color: pink;
    font-size: 26px;
}

.level2 {
    width: 25%;
    background-color: red;
    font-size: 24px;
}

.level3 {
    width: 12.5%;
    background-color: blue;
    font-size: 22px;
}

.level4 {
    width: 6.25%;
    background-color: aqua;
    font-size: 20px;
}

.level5 {
    width: 3.125%;
    background-color: yellow;
    font-size: 18px;
}

.level6 {
    width: 1.5625%;
    background-color: rgb(241, 12, 230);
    font-size: 12px;
}

.layer {
    margin: 20px 0;
    width: 100%;
    text-align: center;
    height: 30px;
}